Generalized Analysis Method for a Class of Novel Wideband Loaded-Stub Phase Shifters

Abstract

In this paper, an analysis method of wideband loaded-stub phase shifters and a fast designing procedure is presented. These kinds of phase shifters use a transmission line loaded with one or two open stubs and a reference line to achieve up to 135° phase shift. Analysis results shows that lower than -10dB return loss and precise phase shift can be achieved over a 100% bandwidth employing the ideal open stubs. To approach the ideal impedance value of the open stubs, an arrow-shaped stub and several means to control its impedance is proposed. As verification of the analysis method, a 90° two-stub loaded phase shifter is easily designed and fabricated. Measured results show the design achieves better than ±4° phase ripple, less than 0.5dB insertion loss, and better than 10dB return loss over an 85% wideband.